A320 flight crew has an altitude deviation due to turbulence during cruise.

Attributes
ACN	732225
Time
Date	200703
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zdv.artcc
State Reference	CO
Altitude	msl single value : 35000
Environment
Weather Elements	Turbulence other
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv.artcc
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	732225
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : turbulence
Independent Detector	other flight crewa other flight crewb
Resolutory Action	none taken : insufficient time
Supplementary
Problem Areas	Weather Aircraft Flight Crew Human Performance
Primary Problem	Ambiguous

Narrative:

Cruise flight; near cruser intersection. We were flying in level flight with light turbulence. The radar was on and showed no returns and there was no reports from other aircraft from other than light turbulence. We hit an area of moderate turbulence with a strong updraft. We were unable to maintain altitude; the aircraft was pushed up 800 to 900 feet. We notified ATC that we were unable to maintain altitude; due to wave actions. Clearing the weather condition; we returned to the assigned altitude. We notified operations and ATC of the WX area. ATC did not indicate any loss of separation between us and any other aircraft.

Original NASA ASRS Text

Title: A320 FLT CREW HAS AN ALT DEV DUE TO TURB DURING CRUISE.

Narrative: CRUISE FLIGHT; NEAR CRUSER INTERSECTION. WE WERE FLYING IN LEVEL FLIGHT WITH LIGHT TURBULENCE. THE RADAR WAS ON AND SHOWED NO RETURNS AND THERE WAS NO REPORTS FROM OTHER AIRCRAFT FROM OTHER THAN LIGHT TURBULENCE. WE HIT AN AREA OF MODERATE TURBULENCE WITH A STRONG UPDRAFT. WE WERE UNABLE TO MAINTAIN ALTITUDE; THE AIRCRAFT WAS PUSHED UP 800 TO 900 FEET. WE NOTIFIED ATC THAT WE WERE UNABLE TO MAINTAIN ALTITUDE; DUE TO WAVE ACTIONS. CLEARING THE WEATHER CONDITION; WE RETURNED TO THE ASSIGNED ALTITUDE. WE NOTIFIED OPS AND ATC OF THE WX AREA. ATC DID NOT INDICATE ANY LOSS OF SEPARATION BETWEEN US AND ANY OTHER AIRCRAFT.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.